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Commit 7b388084 authored by Xishi Qiu's avatar Xishi Qiu Committed by Alex Shi
Browse files

kasan: use IS_ALIGNED in memory_is_poisoned_8() 



Use IS_ALIGNED() to determine whether the shadow span two bytes.  It
generates less code and more readable.  Also add some comments in shadow
check functions.

Signed-off-by: default avatarXishi Qiu <qiuxishi@huawei.com>
Acked-by: default avatarAndrey Ryabinin <aryabinin@virtuozzo.com>
Cc: Andrey Konovalov <adech.fo@gmail.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
(cherry picked from commit 10f702627e139e21465f4c9d44f63527bbca163c)
Signed-off-by: default avatarAlex Shi <alex.shi@linaro.org>
parent 776dee31

mm/kasan/kasan.c

+22 −2
Original line number Diff line number Diff line
@@ -86,6 +86,11 @@ static __always_inline bool memory_is_poisoned_2(unsigned long addr) 
		if (memory_is_poisoned_1(addr + 1))

			return true;



		/*

		 * If single shadow byte covers 2-byte access, we don't

		 * need to do anything more. Otherwise, test the first

		 * shadow byte.

		 */

		if (likely(((addr + 1) & KASAN_SHADOW_MASK) != 0))

			return false;
@@ -103,6 +108,11 @@ static __always_inline bool memory_is_poisoned_4(unsigned long addr) 
		if (memory_is_poisoned_1(addr + 3))

			return true;



		/*

		 * If single shadow byte covers 4-byte access, we don't

		 * need to do anything more. Otherwise, test the first

		 * shadow byte.

		 */

		if (likely(((addr + 3) & KASAN_SHADOW_MASK) >= 3))

			return false;
@@ -120,7 +130,12 @@ static __always_inline bool memory_is_poisoned_8(unsigned long addr) 
		if (memory_is_poisoned_1(addr + 7))

			return true;



		if (likely(((addr + 7) & KASAN_SHADOW_MASK) >= 7))

		/*

		 * If single shadow byte covers 8-byte access, we don't

		 * need to do anything more. Otherwise, test the first

		 * shadow byte.

		 */

		if (likely(IS_ALIGNED(addr, KASAN_SHADOW_SCALE_SIZE)))

			return false;



		return unlikely(*(u8 *)shadow_addr);
@@ -139,7 +154,12 @@ static __always_inline bool memory_is_poisoned_16(unsigned long addr) 
		if (unlikely(shadow_first_bytes))

			return true;



		if (likely(IS_ALIGNED(addr, 8)))

		/*

		 * If two shadow bytes covers 16-byte access, we don't

		 * need to do anything more. Otherwise, test the last

		 * shadow byte.

		 */

		if (likely(IS_ALIGNED(addr, KASAN_SHADOW_SCALE_SIZE)))

			return false;



		return memory_is_poisoned_1(addr + 15);